1. Technical Field
The invention is related to example-based facial sketch generation, and more particularly to a system and process for automatically generating a sketch of a person's face from an image of the person's face that captures the style of a sketch artist whose facial sketches were employed in training the system.
2. Background Art
It is always fascinating to see how a sketch artist draws a picture of someone's face. Sketches are perhaps the simplest form of drawings because they consist of only lines. Somehow the artist can quickly distill the identifying characteristics of a face and highlight them with a small number of strokes.
There have been a few attempts to interactively or automatically synthesize facial sketches. Brennan [1] presented perhaps the first interactive caricature generator. Murakami et al. [2, 3] developed the template-based facial caricature system. Li et al. [4] proposed an automatic facial sketch system that uses a generalized symmetry operator, rectangle filter, and characteristic shapes to detect the locations of facial feature points. However, these approaches, without observing and learning from the artist's products, in general produce stiff and unexpressive sketches.
There have been some attempts to teach a computer to automatically generate a stylistic facial sketch by observing images drawn by artists. For example, Librande [5] developed an example-based character drawing system that can generate many dramatic sketches but is restricted in the types of images it can manipulate. Recently, Freeman et al [6] presented an example-based system for translating a sketch into different styles. However, this system focused on transferring styles instead of generating a stylistic sketch from an image.
No system to date has provided an example-based stylistic facial sketch system that is capable of capturing the subtle styles of a sketch artist's work, and use this information to automatically generate a sketch that exhibits the stylistic characteristics of the sketch artist. The present invention is the first to accomplish this task.
It is noted that in the preceding paragraphs, as well as in the remainder of this specification, the description refers to various individual publications identified by a numeric designator contained within a pair of brackets. For example, such a reference may be identified by reciting, “reference [1]” or simply “[1]”. Multiple references will be identified by a pair of brackets containing more than one designator, for example, [2, 3]. A listing of references including the publications corresponding to each designator can be found at the end of the Detailed Description section.